Electric discharge device



Nov. 17, 1936. G. H. ROCKWOOD, JR

ELECTRIC DISCHARGE DEVICE Filed Oct. 3, 1954 2 Sheets-$heet 1 FIG.

lNVENTO/Q a. H ROCKMDOQJR 8V ATTORNEY Nov. 1 7 1936. G. H. RocKwooD, JR

ELECTRIC DISCHARGE DEVICE Filed Oct. 5, 1934 2 Sheets-Sheet 2 INVENTORa. h. ROG/(W000, /R.

0mm 6 1M ATTORNEY Patented Nov. 17, 1936 UNETED STATES PATENT OFFICEELECTRIC DISCHARGE DEVICE Application October 3, 1934, Serial No.746,631

8 Claims.

This invention relates to electric discharge devices and moreparticularly to such devices of the trigger type wherein the initiationof a discharge between a cathode and an anode is controllable by thepotential of a third electrode.

One object of this invention is to decrease the deionization time inelectric discharge devices of the trigger type.

In electric discharge devices comprising a cathode, an anode, and a gridelectrode, such as disclosed in Patent 1,921,004, granted August 8, 1933to A. L. Samuel, wherein the grid electrode is utilized as a .trigger tocontrol the initiation of a discharge between the cathode and the anode,the deionization'time is dependent in a large measure upon the impedanceof the circuit including the grid electrode and in general the greaterthe impedance of this circuit the longer is the deionization time. It isdesirable frequently, however, to have in the same system a highimpedance circuit including the grid electrode, and also a relativelyshort deionization time.

This desirable combination, that is of high impedance and shortdeionization time, may be attained in accordance with this invention bythe provision of an auxiliary electrode, which may be operated with amomentary large negative bias from a low impedance source and usedsolely for deionization purposes. The grid electrode may be associatedwith a high impedance source and utilized solely -to perform the usualcontrol function.

In one embodiment illustrative of this invention, an electron dischargedevice comprises an enclosing vessel having an ionizable atmospheretherein, an incandescible cathode and a rod-like anode. A cylindricalshell, serving as the control electrode, encompasses the cathode and isprovided with a lateral opening in juxtaposition to the anode, throughwhich the cathode-anode discharge may occur. A deionization electrode,which may be a helical grid or a cylindrical mesh grid, encompasses thecathode and is disposed between the cathode and the control electrode.The deionization electrode preferably comprises closely spaced elements'so that it will present a large surface for collecting positive ionsduring the deionization period.

The invention maybe embodied also in devices, such as disclosed in mycopending application, Serial No. 746,630, filed October 3, 1934,including a plurality of anodes and wherein the cathode, controlelectrode, and anodes are so constructed and arranged that the breakdowncharacteristics of the several anodes are different,

The invention and the features thereof will be understood more clearlyand fully from the following detailed description with reference to theaccompanying drawings in which:

Fig. 1 is a perspective view of an electric discharge deviceillustrative of one embodiment of this invention, portions of thecontrol electrode being broken away to show the inner electrodes moreclearly;

Fig. 2 is a cross-sectional view along the line 22 of the electrodes inthe device illustrated in Fig. 1, showing the configuration and relativedisposition of the electrodes;

Fig. 3 is a perspective view of a modification of the device shown inFigs. 1 and 2, in which the deionization electrode is a cylindrical meshgrid;

Fig. 4 is another perspective view showing the invention embodied in anelectric discharge device including a plurality of anodes havingdifferent breakdown characteristics; and

Fig. 5 is an elevational view in cross-section of the electrode assemblyembodied in the device illustrated in Fig. 4.

Referring now to the drawings, the electric discharge device shown inFig. 1 comprises an enclosing vessel 10 having a stem I I terminating ina press I2 from which the electrodes of the device are supported. Thevessel I is filled with an ionizable medium, such as argon at a pressureof the order of 0.25 millimeter of mercury. An insulating cap or base I3is suitably secured to the enclosing vessel and carries a plurality ofterminal prongs M for associating the electrodes of the device with anexternal circuit.

An equipotential heater type cathode is supported from the press l2 andincludes an insulating core 15 having a heater filament, not shown,threaded therethrough and a metallic sleeve 16 encompassing the core land having a coating of thermionic material, such as barium and stron-,

tium oxides, on its outer surface. The ends I! of the heater filamentare secured to rigid wires l8 embedded in the press 12 and electricallyconnected to two of the terminal prongs M by conductors IS. The cathodesleeve 16 is provided at opposite ends with integral extensions 20 and2|, the extension 20 serving as a leading-in conductor and being afiixedto a metallic stub or wire 22 embedded in the press l2 and electricallyassociated with one of the terminal prongs M by a conductor 23. Theother extension 2| is secured to a bent metallic stub 24 which isembedded in an insulating bead 25 supported from a metallic upright orrod 26 extending from the press, by a short wire 21.

Supported from the upright or rod 26 is a control electrode comprising acylindrical portion 28 having a lateral opening 29 and coaxiallydisposed about the cathode, and a fiange portion 30 suitably secured tothe upright or rod 26, as by Welding. The upright or rod 26 iselectrically connected to one of the terminal prongs I l by a conductor3! and serves as the lead-in for the control electrode. 7

A metallic rod 32 is embedded at one end in the press l2 and extends inproximity to the, v opening 29, the rod serving as the anode of thedevice and being connected to one of the terminal prongs l4 by aconductor 33. In order to prevent discharges between the cathode and theanode through the lower end of the control electrode, the lower portionof the rod anode 32 is encased in an insulating sleeve 34, such as aglass tube.

As described in detail in the aforementioned Samuel patent, theelectrode 28 may be utilized .as a trigger to control the initiation ofa discharge between the cathode l6 and the anode 32, the controlcharacteristics'of the electrode 23 being dependent upon the area of theopening 29, The'deionization time of a device thus operated, that is theperiod required to reduce the number of positive'ions in thecathode-anode field sufficiently to render the device non-conductive, isdependent in large measure upon the impedance of the circuit includingthe control electrode, and in general the greater the impedance of thiscircuit, the longer'the deionization time. It is frequently desirable,however, to have a relatively short deionization time in such devicesincluded in systems wherein the impedance of the control electrodecircuit is relatively great.

In accordance with this invention, the short deionization time isobtained by providing an auxiliary or deionization electrode, which maybe operated with a momentary large negative bias from a low impedancesource, serving to rapidly reduce the number. of 'the cathode-anodefield.

In one form, as shown in Fig. 1, the auxiliary or deionization electrodemay be a helical wire grid 35 disposed between the cathode it andpositive ions in control electrode "28 and coaxial therewith. The grid35 is carried by a rigid metallic upright or rod 36, which is supportedat one end by a rigid metallic stub or wire 31 embedded in theinsulating bead 25 and is coupled to the upright or rod 26 through rigidwires or stubs 38 and 39 embedded in an insulating bead 40.

The auxiliary or deionization electrode is electrically connected to aterminal cap 4! afiixed to the enclosing vessel I0, by a conductor 42affixed to the cap 4! and to the wire or stub 37.

p In order that the grid 35 will present a large surface for collectingpositive ions during the deionization period, the turns thereofpreferably are closely spaced. For example, if the ionizable embodimentof the invention illustrated in Fig. As shown in Fig. 3, to'maintain theproper relative position of the several electrodes more positively, theinsulating bead 25 may be coupled to the anode 32 by a rigid wire orstub 44,

M by a conductor 52.

The invention may be embodied also in electric discharge devices of thetype disclosed in my copending application Serial No. 746,630, filedOctober 3, 1934, comprising a plurality of anodes having differentbreakdown characteristics. A device illustrative of this type isillustrated in Figs. 4 and 5 and comprises an enclosing vessel 45 havinga stem terminating in a press 46 from which a unitary electrode assemblyis supported. This assembly includes a control electrode having acylindrical portion 41 provided with diametrically opposite apertures 68and 49 of unequal areas, and supporting flanges 50 which are suitablysecured, as by welding, to uprights or rods 5| embedded in and extendingfrom the' press 12, one of the uprights or rods being electricallyconnected to one of the terminal prongs Insulating members 53 and 54,such as mica discs, extend across the ends of and are seated against thecontrol electrode and carry a pair of metallic rods 55 and 56 whichextend through the insulating discs and are secured thereto by eyelets51. The rods 55 and 56, which constitute anodes of the device, aredisposed in alignment with the apertures 48 and t9 and are electricallyconnected with two of the terminal prongs M by conductors 58 and 59respectively sealed in the press 43.

Disposed within the cylindrical portion 41 of the control electrode andcoaxial therewith is an equipotential cathode including a metallicsleeve 50 coated with a thermionic material and extending through acentral aperture in the insulating disc 54. The sleeve 60 is afiixed atits upper end to a short guide or wire 6| which extends through acentral aperture in the upper insulating disc 53. Attached to the lowerend of the metallic sleeve 60 is a flattened bell shaped shield 62 whichencloses the leading-in conductors 18 for the cathode heater filamentand is carried by two rigid metallic members or wires 63 embedded in thepress, one of the metallic members or wires 6| beingelectrically'connected to the metallic sleeve 60 by a tie wire 64 and toone of the terminal prongs M by a conductor 65. In some cases it isdesirable to operate the heater filament positive with respect to thecathode, and in such cases the shield 62 serves to prevent theestablishment of a discharge between the heater filament and thecathode.

A helical wire deionization electrode 66 encompasses the cathode 60 andis supported by two uprights or wires Tl which are fitted in aperturesin the insulating discs 53 and 54. One of the uprights or wires 11 iselectrically connected to a terminal cap 4| by a conductor 42.

Although specific embodiments of the invention have been shown anddescribed it will be understood, of course, that modifications may bemade therein without departing from the scope or spirit of thisinvention as defined in the appended claims.

What is claimed is:

1. An electric trigger device comprising an enclosing vessel having anionizable atmosphere therein, a cathode, a cylindrical control electrodeencompassing said cathode and having a lateral discharge openingtherein, an anode in juxtaposition to said opening, and a deionizationelectrode encompassing said cathode and disposed between said cathodeand said control electrode, said deionization electrode being composedof a plurality of metallic elements spaced closely adjacent to provide alarge area surface for the collection of positive ions.

2. An electric discharge device comprising an enclosing vessel having anionizable atmosphere therein, a linear incandescible cathode, a rodlikeanode parallel to said cathode, a cylindrical control electrode betweensaid cathode and anode and encompassing said cathode, and a helicaldeionization grid within said control electrode and encompassing saidcathode, the turns of said grid being spaced of the order of 0.5millimeter from each other.

3. An electric discharge device comprising an enclosing vessel having anionizable atmosphere therein, a linear cathode, a shell electrodeencompassing said cathode and coaxial therewith, said shell electrodehaving a lateral discharge opening, a rod anode outside of said shellelectrode and disposed in alignment with said cathode and said opening,and a cylindrical electrode between said cathode and said shellelectrode and coaxial therewith, said cylindrical electrode beingperforated to provide an unimpeded discharge path between said cathodeand said anode through said lateral opening.

4. An electric discharge device comprising an enclosing vessel having astem and having also an ionizable atmosphere therein, a supportextending from said stem, a cylindrical shell electrode carried by saidsupport, said shell electrode having a lateral opening, insulatingmembers mounted on said support in spaced relation, a cathode withinsaid shell electrode and coupled to one of said insulating members, ananode outside of said shell electrode and in alignment with saidopening, and a cylindrical electrode supported from said insulatingmembers, disposed within said shell electrode and encompassing saidcathode, said cylindrical electrode being perforated to provide anunimpeded discharge path between said cathode and said anode throughsaid lateral opening.

5. An electric discharge device comprising an enclosing vessel having astem and having also an ionizable atmosphere therein, a supportextending from said stem, a shell electrode carried by said support andhaving a lateral opening, a pair of insulating members carried by saidsupport and disposed adjacent opposite ends of said shell electrode, arigid member within said shell electrode and supported from saidinsulating members, a cylindrical grid carried by said rigid member anddisposed within said shell electrode,

a cathode within said grid and supported from one of said insulatingmembers, and an anode outside of said shell electrode and injuxtaposition to said opening, said grid being perforated toprovide anunimpeded discharge path between said cathode and said anode throughsaid opening.

6. An electric discharge device comprising an enclosing vessel having anionizable atmosphere therein, a cathode, a plurality of anodes, a shellcontrol electrode between said cathode and said anodes, said controlelectrode having a plurality of apertures of unequal areas disposed eachin juxtaposition to a corresponding one of said anodes, and adeionization electrode between said cathode and said control electrode.

7. An electric discharge device comprising an enclosing vessel having anatmosphere of argon at a pressure of the order of 0.25 millimeter ofmercury therein, a cylindrical shell control electrode having a lateralopening, insulating members extending across the ends of said controlelectrode, a cathode and a helical grid electrode disposed within saidcontrol electrode and positioned by said insulating members, the turnsof said helical grid being spaced approximately 0.5 millimeter from eachother, and an anode disposed in alignment with said opening, said anodeextending between said insulating members and being supported thereby.

8. An electric discharge device comprisng an enclosing vessel having astem, said vessel having an ionizable atmosphere therein, a plurality ofsupports extending from said stem, a rigid control electrode carried bysaid supports and in cluding a cylindrical portion having lateralapertures of unequal areas, insulating discs extending across and seatedagainst opposite ends of said cylindrical portion, a plurality of rodanodes extending between and carried by said insulating discs, each ofsaid anodes being disposed in juxtaposition to a corresponding one ofsaid apertures", a cathode within said cylindrical portion and havingend portions fitted in said insulating discs, a plurality of rigiduprights disposed within said cylindrical portion and fitted at oppositeends in said insulating discs, and a helical deionization electrodecarried by said uprights and encompassing said cathode.

GEORGE H. ROCKWOOD, JR.

